Interactive Voice Response (IVR) systems are an important tool for customer relationship management and play a critical role in providing information and features to existing and potential business customers who use the telephone as an interface to an enterprise. IVR systems allow efficient exchange of information with reduced human interaction.
An Interactive Voice Response, also known as a Voice Response Unit, is a computer application that allows callers to interact with a communications system over the telephone. The IVR answers a call by playing one or more pre-recorded messages or scripts. The messages usually prompt the caller to provide input either verbally or by pressing touchtone keys. The IVR supplies the caller with information based on the responses. Examples of well known uses of IVR systems include automated answering services, electronic voice mail, automated ticket ordering or recorded timetable information.
In a multi-channel IVR system, data used by the IVR to respond to a caller is often stored in a database accessible by a data processing system on which runs the IVR applications. The dialogs that control the interaction between a caller and the data can be provided in many different application programming environments including Java™, (Java is a trade mark of Sun Corporation), and VoiceXML (Voice extensible Markup Language), as well as state tables. It has been found that multi-channel IVR systems, especially those using Java and VoiceXML, can easily become overloaded. At present, when a critical system load is detected channels are disabled to protect the system. Manual intervention is then usually required to return the system to a working state.
One system which attempts to overcome the problem of overloading a multi-channel IVR is described in US 2003/0114166. This system employs a switching centre to control an external switching technology resource. The switching centre is controlled so as to block and release ports between the switching centre and the external resource according to a capacity utilisation of the resource. This can cause disruption of calls when the channel on which a call is being carried out is suddenly blocked by the switching centre.
The present invention aims to provide an improved system and method for managing load in a telephony system with minimum disruption of calls. Rather than blocking a busy channel, the invention marks channels for disablement, and disables them only once the current call has finished. Preferred features are that the system is stateless, in that it does not need to know details of what it has done before, that it iteratively finds the optimum level of channel/system usage, and that it can work without the need for a separate signalling link, so can thus be used with Channel Associated Signal (CAS) protocols.
The invention can be applied both to systems where all channels are in use, as well as systems that may not be using all channels. For systems in which all channels are in use, one method which can be used to reduce system load is to take actions that increase the effective length of the calls, for example by adding in a waiting message. However, if not all channels are in use, increasing the call length would have the effect of driving new users onto the idle channels, rather than reducing the utilisation of system resources. Indeed, it may have the opposite effect as the system will have to maintain more open dialogs to different users.
IVR systems typically have a limited number of channels which are available, for example 480 channels. At times, for example when a central processing unit, on which an IVR is running, is also carrying out a data backup, a large amount of the processing capacity available is being used to do the backup. Thus there may not be sufficient processing capacity to maintain all 480 channels, and thus a system overload can occur even when the system is not using all channels.